Improvement in valve-gears for steam - engines



Uurrnn sTA'IES GEORGE H. COBLISS, OF PROVIDENCE, RHODE ISLAND.

IMPROVEMENT IN VALVE-GEARS FOR STEAM-ENGINES,

Specification forming part of Letters Patent No. 177,059, dated May 9, 1876; application filed 7 January 10, 1876.

' have invented certain new and useful Improvements relating to Steam-Engines, of

which the following is a specification:

They may apply to all that class of engines in which separate valves are employed at each endof the cylinder, one for the induction and the other for the educ'tion of steam. I will show themas applied to the class in which the valves turn in their seats in amanner analogous to a stop-cock. The parts which communicate motion to the exhaust-valve form the subject of a separate application for patent. This specificationrelates to the operation of the steam-valves. I The accompanying drawings represent what I consider the best means of carrying out the invention.

v Figure 1 is a side elevation. Fig. 2 is a cross-section of a portion on a largenscale, and Fig. 3 is a corresponding longitudinal section.

Si milar letters of reference indicate like parts in all the figures.

.A is the fixed frame-work. B B are the ex haust-valve shafts and their arms; and O are,

links connecting them, respectively, to rocking levers turning on the studs d, the two arms of which are each marked, respectively, 1) D These levers perform an important function, not only in opening the exhaust-valve, but also in opening and liberating the steamvalves. They each receive motion i'roina common rock-shaft, m, through links E, which connect the pins 0 on the wheelM with the pins 1 d on the arm I). The shafts of the steam- .is mounted on the rod Gr. There is a corresponding mechanism at each end of the cylinder, which may be all operated from the rockshaft m. I will describe one end only. A pin,

W, is set in each of the lever-arms D at the point represented, considerably below the line joining d and d 9 A rod, H, connects this pin 61 with a suitable pin or a knuckle-joint in a lever, I, which-turns on a fixed center, i, favol-ably mounted for engagement with the hook Q. The lever I is channeled on its upper side, to afford a proper bearing and lateral guide for a push-ofl' rod, L, which lies therein, and is knuckled to the vertical arm of the bellcrank lever J, turning on a center, j, and 0perated by connection to a rod, K, which latteris elevated and depressed by a governor. (Not represented.) 1

As the shaft or rocks in its seat, each depression of a pin, 6, lowers the corresponding arm D rod H, and lever I. The succeeding ascent of. all these parts engages the lever I with the hook Q, and turns the valveshaft Pin the direction to open the valve. This motion continues to openthe valve with a rapid and reliable motion at an invariable point in the stroke, continuing to open itfarther until the pusher-rod L detaches the hook Q, by pressing it gently out of engagement With the lever I, in opposition to the force of the spring G. This period arrives sooner or later,according as the lever J is adjusted by the elevation or depression of the governor-rod K.

- The point of engagement of the lever l with the hook Q is formed by a piece of steel, 1 :which is secured by'a bolt, I and has two acting edges, beveled or bent in opposite directions, and may be reversed when one edge becomes worn.

Instead of a weight on the rod G, it is pref erable to employ a piston, subject to a more thus available might induce a more rapid turning of the valve. The piup should be near what is termed the center of gyration of the arm 1? and its attached shaft and hook. The pin (1 should be so low that it is rising rapidly near the middle of the stroke of the main piston. (N ot'rep'resented.)

Someof the advantages due to certain features of the invention maybe separately enumerated as follows: First, by reason of the fact that the force transmitted through the rod G, to induce the instantaneous closin g motion, is applied at the point 19 at or near or less perfect vacuum beneath, as the force r is centered considerably'above; the engaging-w the center of gyration of the-valueshaft and its attachments, the inertia of those partsis; overcome in the most direct manner, both in giving and arresting motion, with little strain on the bearings of the shaft D, or of any other part. Second, by: reason of. the fact thatthe. spring G, actuating" the hook Q, is mounted 13 on the clgsing rod G, rather than on the "alve arm, I maintain anearly equal force: on i the hook in all positions. Third, my intermediate lever I, tnrniiig on a separate center, 17, from the "alyezstem, relieves the latter from much of the strain to which it" would 'otli'erwisebe subjected. Fourth, by reason of the double construction of the lever I, it guides the pusher-rodL, and insuresthe proper lateral posie tion thereof. Fifth, byreasonof the pusher rod Land its operating lever'Land ofiitsccon' nection to the governor rodiiKmsshownfl am ableto effect the pointotcut-otli.bytlierelevw tion and depressionot'the: governor-rod K', in a manner more nearlyproportionate to'tlie'; ,l quantities ofsteanrrequired tlianzthe ordinary arrangement. The factthat thetpushenrothli lever Land thativthe center, whicliis'zthepoint" i of connection of'Iz to"J,m'o ves"i1ra practically. horizontal line asthe: speedof'tlie enginerina creases and diminishes, cau'sesthe hook-'ro'dQ to be disconnected with certainty,eithernear the beginning of the stroke: of the: piston, or near the middle of'its-stroke', with justaboutf theproper amount of variationfor agivenvvw riatiou in speed in all positions Sixth, by reason of the connectionofftiiet'levers l and D bythe rod H, as shown, I' operate the: steam-valve through the mediumoftliesexe 5- haust-valve lever, and thus not only siinpliiy the machinery, but also, by virtue of the wrist-plate, motion, due-to the lbwpointofiftlie: i connection d to thelever D, obtaiuaslowf motion of the lever-I near the'commencement,j and a rapid meveinent'. near" the; close,- of? its 1 rising motion,

By mounting the springGon the. rod G q I obtain highly" desirably conditions; in: regard to it's'rtension at different periods. The-lever Lain its, descending motion, necessarilyacts: \vitlifits catch against the;t'ullfpart'oftheihook. Q, pushing-"it away. During this periodtliew parts stand in such position that in conse quence of the mounting off the springG"on the rod G its force: on the" hook Q is' slight. This condition is indicated on theileft' sideof the drawing, Fig. 1; but; during the? period, While the hook is held engagedtwith thelever' g I, and is about being pushed 011', the tension of the. spring.is=strongandiuniform...a No slight orce can disengagerthei hook; Itiis snre to remain engaged untilitis positively pushed off by the actual firm contact of the pusher L,

after alllost motion, &c.,has been taken up, i

The slight effect whichthespring produces on the positiorrot tlie" governor i's also uniform in all changes of the point'of cut-off.

, 'Itis-important=to maintainhthei position of the shaft of a rolling valve very exactly. The ordinary modes for communicating motion to such valve impose a strain on thisshaft, which I avoid bymyindep'endentllyamounted lever I. A By the interposition of thelevers J between the pushers L and the linksconnecting tOItHB governor-rod K, the tendency to disturb ithe position of the governouyiiy the? force 'requi red to" disengage the: bookie? red need to an almost inappreciahle? amount, "ami is; hy*'tlie-* positionr ofth'e links-and tlierlever-arm;madefpracti By reaso'rr'ot my connection H icoinmunicatingbeitweenr" the: point; d fland the knuckle on the lever'I, a propermotion is? communicated to the: latter: bromine-end reliable mechanism;

I claim a as m gi s as herein specifiedi 21 In combination" witliftlie turning arm lPQ'fi hook Q, and operatingrod 'fl ,the-leverll turnin g ion a-stn'dit, distinct: from? thea'valire-st'em P, as'liereiiI-specified'."

The lever I, channeled or duplex,,;as"

shown, with thet'reversible" piece-Iain combi nation withithe hook;Qandvalvearm" P s peciti'ed.

4. Theintermediate levers J,bet.ween the governor-rod and pu'sher reds T1,; in combination with the,saine, ,and witliivtlle"vibrating levers: I andtlie engagin ghouksi Q, connected witlithe valve=ar1ns P, astherein specifiedi a 5; The operatingLmeans rM 'Efi exhaust-valve leveruD B intermediate rod H, and steam valveeoperatingvleverI and its connections,

combined and" arranged 1 toiqserveas and: for

the purposesliereiirspecifiedlx In testiinonywliereoFT havewhereunto set presenceiqof two: subscribingwitnesses:

, GEO. H; GOREISS:

Witnesses THOMAS D; STE'rsoN, En; W. RAYNSFORD.

y iinprovemeirts ih "steam-en: 

